Ameer Hamza 1eace59060 libzfs: use mount_setattr for selective remount including legacy mounts ... When a namespace property is changed via zfs set, libzfs remounts the filesystem to propagate the new VFS mount flags. The current approach uses mount(2) with MS_REMOUNT, which reads all namespace properties from ZFS and applies them together. This has two problems: 1. Linux VFS resets unspecified per-mount flags on remount. If an administrator sets a temporary flag (e.g. mount -o remount,noatime), a subsequent zfs set on any namespace property clobbers it. 2. Two concurrent zfs set operations on different namespace properties can overwrite each other's mount flags. Additionally, legacy datasets (mountpoint=legacy) were never remounted on namespace property changes since zfs_is_mountable() returns false for them. Add zfs_mount_setattr() which uses mount_setattr(2) to selectively update only the mount flags that correspond to the changed property. For legacy datasets, /proc/mounts is iterated to update all mountpoints. On kernels without mount_setattr (ENOSYS), non-legacy datasets fall back to a full remount; legacy mounts are skipped to avoid clobbering temporary flags. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com> Signed-off-by: Ameer Hamza <ahamza@ixsystems.com> Closes #18257		2026-03-09 11:06:22 -07:00
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freebsd	libzfs: use mount_setattr for selective remount including legacy mounts	2026-03-09 11:06:22 -07:00
linux	libzfs: use mount_setattr for selective remount including legacy mounts	2026-03-09 11:06:22 -07:00